Only a fool will try to have an argument with his mother.
She is right no matter what - that is what she believes - prove her wrong and she still will believe from the bottom of her heart that she is right.
You can do a tons of stuff like remind her that you don't say anything about the stuff that she puts on her hair and will cause cancer, MS, Alzheimer's dementia and he wearing diapers.
You can show her research endorsed by Jesus, Mohamed and Buda and that will mean nothing.
Or you can smile nod and go about your day doing whatever you have to do.
Pick one that fits better you case.
100% of the time teh last option is teh better.
Overall parents have higher bitching rights they cleaned our butts when we where small and will do it again if nedded when we are grow ups.